var a
var b 
Page({
   data:{
     result: ''
   },
   plus:function(){
       var c = parseInt(a) + parseInt(b)
       this.setData({
           result: c
       })
       console.log("a + b = " + c)
   },
   getA: function(event){
        a=event.detail.value
        console.log("a= "+a)
   },
   getB: function(event){
        b=event.detail.value
        console.log("b= "+b)
   }

})